This invention relates to stabilizers for vehicles and has particular relationship to stabilizers of the type having a hydropneumatic suspension. Among the vehicles which have a hydropneumatic suspension are the Citroen. It is anticipated that the Mercedes Benz will also have hydropneumatic suspension. The hydropneumatic suspension suspends the body from the wheel base. Such a suspension includes a spring accumulator; a body having chambers separated by a membrane. In one chamber an hydraulic liquid is injected; in the other there is gas whose pressure counteracts the pressure of the hydraulic liquid.
At the outset it appears desirable to define several of the expressions used in this application. A vehicle is said to have an unsprung mass and a sprung mass. The unsprung mass is predominately the axles of the vehicle or other support of its wheels and the parts rigidly secured to the axles or to this other support. The sprung mass is the body of the vehicle and the parts connected thereto. The sprung mass is resiliently suspended from the unsprung mass. The "ends" of a vehicle or of the sprung mass are the front end and the rear end of the vehicle or the sprung mass. The corners of the vehicle or sprung mass are at the terminals of the ends. The expression "opposite corner" means the corner at the same end as the reference corner or the corner diagonal to the reference corner.
This invention concerns itself with anti-roll stabilization. In accordance with the teachings of the prior art, there have been provided anti-roll or banking devices which operate in combination with power-operated inertia stabilizers. Such devices which have been marked by technical success and have been provided by the inventor whose invention is disclosed in this application and by others. Such anti-roll devices are complicated and demand excessive quantities of hydraulic power, an undesirable property in the light of the current energy shortage.
With the advent of the hydropneumatic suspension in Europe about twenty years ago, excellent vertical-ride performance equivalent to that of the inertia power stabilizer was achieved. However, vehicles equipped with such suspensions have excessive roll on turns. To overcome this deficiency a very stiff roll torsion bar was included. This added high stiffness for roll but none for vertical movements. The roll bar has not proven satisfactory because it severely impedes individual movement of the wheels.
It is an object of this invention to overcome the disadvantages, deficiencies and drawbacks of the prior art.
It is also an object of this invention to provide, in a vehicle having soft hydropneumatic suspension, facilities having low power consumption to prevent roll-out on turns which shall operate without binding the free independent movement of the wheels of the vehicle.
It is another object of this invention to provide, for a vehicle including a hydropneumatic suspension, anti-roll means which shall impress great anti-roll forces in a simple manner. Another object is to provide proper damping means for the vertical and angular modes of both sprung and unsprung masses of a vehicle with such anti-roll means. A further object is to provide in such a vehicle integral leveling or height control of the sprung mass to accomodate changes in loading with uniform time delay of such leveling. Still another object is to provide an anti-roll hydropneumatic suspension means with only three working pressure chambers. Yet another object is to provide for such anti-roll means a pendular-valve system with very high speed of response and with damping means for the pendulum having linear characteristic independent of the fluid viscosity. An important object of the invention is to provide a pendulous anti-roll device for a vehicle including hydropneumatic suspension in which a pendulum has a large radius of gyration with great moment of inertia and small pendulous height. Another object is to provide a vehicle including a hydropneumatic suspension with anti-roll means, a positive mechanical lock-out to prevent body sag when the hydraulic power source is idle. An important object is to present a very soft hydropneumatic suspension system with powerful anti-roll means, but whose power consumption is comparable to that of present passive shock absorbers.